This invention relates to new injectable pharmaceutical formulations containing partricin derivatives as the active ingredient. In particular, the new pharmaceutical formulations enclose at least one derivative of partricin in the form of a free base, or a pharmaceutically acceptable water-soluble salt of it, in a solubilizing/dispersing medium made up of a lipid and/or phospholipid emulsion in water.
In patent applications EP-A-0434943 (equivalent to U.S. Pat. No. 5,296,597) and EP-A-0489308 (equivalent to U.S. Pat. No. 5,298,495) several derivatives of partricin A and/or B (henceforth xe2x80x9cpartricinxe2x80x9d) are described, wherein the carboxyl in position C-18 of the macrolidic ring is in the form of an ester or of a neutral amide or of an amide containing a basic nitrogen group in the side chain and where the primary amino group of mycosamine can optionally form an amide bond with the carboxyl of an acid, it too containing a basic nitrogen group in the chain.
The afore-said documents also describe the preparation of their salts with acids, acceptable from a pharmacological and pharmaceutical point of view, and report that such salts are unusually water-soluble.
It has already been ascertained that the partricin derivatives, described in the afore-said European patent applications, can also be used in clinical practice, for human and veterinary application as drugs for treatment of several pathologies sensitive to the partricin derivatives; in particular, injectable formulations may be prepared enclosing such derivatives, evidencing the advantages deriving from the water-solubility of the said partricin derivatives. These formulations may permit, for instance, using a derivative of partricin""s as the active ingredient (e.g., N-dimethylaminoacetyl-partricin A 2-dimethylamino-ethylamide diascorbatexe2x80x94code name SPA-S-843) for instance with the addition of ascorbic acid, as antioxidant, and of lactose as excipient. The freeze-dried product is normally dissolved in 5% glucose solution at the time of use and administered by slow intravenous infusion.
Even though this formulation can be of concrete utility in the clinical practice, it was however found that such aqueous formulations of partricin derivatives, specially when repeatedly administered and with daily frequency, can cause local vascular damage with considerable pain at the site of injection, tissue irritation, edema formation and thickening of vasal epithelium, leading in the end, to massive formation of thrombi and onset of frank thrombophlebitic forms.
It has now been surprisingly found that these side effects involving the vascular system, brought about by intravenous injections of known formulations of the partricin derivatives, can be considerably limited, or even avoided, by the use of new formulations wherein the partricin derivative is enclosed in a lipid and/or phospholipid emulsion in water.
One of the subjects of the present invention is in fact an injectable pharmaceutical formulation enclosing at least one partricin derivative in the form of free basexe2x80x94or of water-soluble pharmaceutically acceptable salt thereof, with acids that are acceptable from a pharmaceutical and pharmacological point of viewxe2x80x94in a solubilizing/dispersing medium made up of a lipid and/or phospholipid emulsion in water such that the resulting emulsion be iso-osmotic.
In the present invention the expression xe2x80x9cpartricin derivativexe2x80x9d indicates the derivatives of partricin described in patent applications EP-A-0434943, EP-A-0489308, GB-A-1359473 (equivalent to U.S. Pat. No. 3,780,173) and GB-A-1046774 (equivalent to U.S. Pat. No. 3,961,047). In particular, preferred formulations are those wherein the partricin derivative is a derivative of partricin A and/or B presenting the carboxyl in position C18 of the macrolidic ring in the form of ester or of neutral amide or of amide containing a basic nitrogen group in the side chain, and those wherein the derivative is further substituted, on the primary amino group of mycosamine in the form of amide with an acid containing a basic nitrogen group in the side chain. A partricin derivative specially preferred for the formulations of the invention is N-dimethylaminoacetyl-partricin A 2-dimethylamino-ethylamide. When the formulations of the invention enclose a partricin derivative in the form of a free base, the addition of a surfactant and/or a co-solvent is preferred in order to avoid any eventual problem of active ingredient solubilization before its inclusion in the lipid emulsion; alternatively, this trouble can be avoided by sonication of the particles, elevation of the system temperature e.g., from room temperature to 40-50xc2x0 C., and etc.
In the case the formulations of the invention enclosed a pharmaceutically acceptable salt of the partricin derivative, these salts are preferably formed with at least one, preferably two, acid equivalents, preferably ascorbic or aspartic acid; the salt preferred for the formulations of the invention is N-dimethylaminoacetyl-partricin A 2-dimethylamino-ethylamide diascorbate, as such or as its free base.
The formulations of the invention comprise a pharmaceutically effective quantity of the partricin derivative; the dose of partricin derivative per unit to be administered remains substantially equal to that of the traditional formulations. In particular, the quantity ranges from 1 to 100 mg, preferably 10 to 50 mg.
The partricin derivative enclosed in the formulations of the invention is, preferably, in the form of solution, of micellar pseudosolution, of encapsulated inclusion compound, or of suspension of sub-micronized particles, their size being smaller than 5 xcexcm. preferably smaller or equal to 3 xcexcm, to avert the risk of pulmonary embolism; following sterilization (by sterilizing filtration or other suitable method), the partricin derivative can directly be added to the lipid emulsion or, preferably, stored in the dry state, following suitable processing (e.g., through freeze-drying), to improve long-term stability and be added to the lipid emulsion just prior to its therapeutic use by parenteral injection, particularly intravasal and, preferably, intravenous route.
In the formulation of the invention, the solubilizing/dispersing medium, is a lipid emulsion, preferably oil-in-water, containing lipids and/or phospholipids, in the form of droplets, vesicles, nanospheres, etc.
The lipids and/or phospholipids used in the formulations of the present invention can be from different origin, that is, animal and/or vegetable and/or synthetic and/or semisynthetic origin (hydrogenated fats and the like).
The lipids are preferably taken from the group of the mono-, di- or triglycerides; specially triglycerides; when of vegetable origin preferably from olives, for instance triolein, or from soybeans, when of animal origin preferably fish oils.
The phospholipids, in particular the phosphatidylcholines, when of vegetable origin are typically soybean lecithins, when of animal origin are selected preferably from egg yolk lecithins.
Other phospholipids, preferred for the formulations of the invention, are those selected from the group of the distearoilphosphatidyl-choline, dimyristoilphosphatidylcholine, dimyristoilphosphatidylglycerol, phosphatidyl-ethanolamine, phosphatidylserine, phosphatidyl-inositol.
Hydrogenate lipids and/or phospholipids too can be used in the formulations of the invention.
When phospholipids are used alone, they can be in the form of multilamellar or unilamellar, large or small vesicles, optionally containing sterols. In other cases, lipids and/or phospholipids can be present in the form of lipid nanospheres able to encapsulate the partricin derivative.
The concentration of the lipids eventually present in the formulations of the invention varies from 1 to 25%, being it usually 10-20% while the concentration of the phospholipids eventually present can vary from 0.05% to 5%.
The formulations of the invention can also enclose an excipient and/or a pharmaceutically acceptable adjuvant, such as those commonly used in the formulations intended for injectable use and according to the evidence of the experts in the field, for instance selected from the sugar group, preferably lactose, glucose, saccharose, maltose; antioxidants, preferably ascorbic acid, sodium ascorbate, vitamin E; preservatives, preferably alkyl paraben, benzyl alcohol; ionic or non-ionic surfactants, preferably sodium laurylsulfate, sodium deoxycholate, Tween(copyright), particularly Tween 80, polysorbates, Cremophor (LE or other); acid or neutral or basic buffers, preferably mono- or bi-basic phosphates; co-solvents; stabilizers; polyalcohols such as i.e. glycerol, mannitol and xylitol; sterols such as cholesterol.
The formulations of the invention can moreover be realized in both a pharmaceutical form wherein the partricin derivative is already inserted in the lipid and/or phospholipid emulsion together with any eventual excipient and/or adjuvant, and in a pharmaceutical form wherein the partricin derivative is preserved in an anhydrous state (in the form, for instance, of a lyophile), together with any eventual excipient and/or adjuvant, separated from the lipid and/or phospholipid emulsion, together with any eventual excipient and/or adjuvant, in which it is extempore inserted before therapeutic administration.
The formulations of the invention are useful to prepare a medicament intended for the clinical treatment of pathologies sensitive to the action of the partricin derivative, such as, f.i., those described in EP-A-0434943, EP-A-0489308, GB-A-1359473 and GB-A-1046774 and several other pathologies. The texts of the four a/m documents are incorporated, for reference, in the present description, in particular as regards the partricin derivatives, their preparations and their described uses.
All the above mentioned products (lipids, phospholipids, excipients etc.) are commercially available and must be specially purified, fractioned and declared suitable for the injectable use (non pyrogenic etc.) The final composition should be such as to conduct to an iso-osmotic emulsion.
Industrial preparation of the emulsions requires the use of special equipment such as, in example, colloidal mills, two-stage pressure homogenizers, ultrasound generators, as is evident to an expert in the sector. Special attention will have to be paid to size control of the particles in suspension (sub-micron dimensions or, at any rate, not greater than 3-5 xcexcm), to their distribution interval and their homogeneity, as well as stability of the emulsion itself, as is evident to an expert of the sector.
An additional item of the present invention consists in a procedure for preparation of the formulations of the invention, comprising sterilizationxe2x80x94preferably by sterilizing filtration of the solution, micellar pseudo-solution, encapsulated compound or suspension of sub-micronized particles of the partricin derivativexe2x80x94and subsequent inclusion in the lipid and/or phospholipid emulsion.
Moreover, drying of the derivative is preferredxe2x80x94subsequent to sterilization and, at any rate, before inclusion in the lipid and/or phospholipid emulsion, of the solution, pseudo-solution or suspension of the partricin derivativexe2x80x94preferably through freeze-drying.
In the case that the partricin derivative be in the form of a free base, the procedure according to the invention can also comprise the addition of a surface active agent and/or a co-solvent to the partricin derivative or sonication of the particles or rising of the system temperature, passing, i.e., from room temperature to 40xc2x0-50xc2x0 C., before inclusion of the derivative into the lipid and/or phospholipid emulsion. Incorporation of the drug in the lipid emulsion can occur in both the presence of the partricin derivative in the form of a solution, and in the solid state: in the latter case, the solid, for example a freeze-dried substance, can first be dissolved or dispersed in sterile water and the solution added to the emulsion or, better still, it can be directly solubilized with a portion of it. The final preparation will be sterile.
The final volume of the injectable formulation of the invention varies, in general from 5-10 ml when intended for bolus administration, to 100, 250, 500 ml when intended for slow, drip infusion over 1-5 hours, as evident to an expert of the sector.
As already mentioned, the formulations of the invention can unexpectedly reduce and even eliminate, the local irritating effects when used by intravascular route, contrary to what commonly occurs when using more traditional formulations as those obtained in glucose solution (5% glucose solution) or in physiological solution (0.9% sodium chloride solution). Moreover, the formulations of the invention allow, for instance, incorporation of the more lipophylic (hydrophobic) derivatives of partricin, in particular if in the form of free bases, in the inner oily phase of the oil-in-water emulsion, enabling the derivatives to be released over longer times and with particular tropism for the cells of the reticuloendothelial system and for the organs rich thereof, with relative decrease of the blood levels and wide changes of their toxicity. Viceversa, the more hydrophilic derivatives, along with their water soluble salts, specially when maintained in an acid pH medium, remain in the outer aqueous phase of the same oil-in-water emulsions, and retain their distribution in the body fluids substantially unchanged.
The following examples illustrate the invention without limiting it.